A vertical blanking interval (VBI) signal testing tool captures, isolates, and analyzes a VBI signal to determine the quality of the VBI signal or signal source. A digitized VBI signal is received and analyzed according to industry standards. The VBI signal is first examined using thresholds, threshold points, and other points as a way of discerning waveforms in the signal and their individual characteristics. Thereafter, deviations of the VBI signal from industry standards are logged or displayed for review.